SEMICONDUCTOR CHIP AND METHOD OF ESTIMATING CAPABILITY OF SEMICONDUCTOR MANUFACTURING SYSTEM
A method of estimating the capability of a semiconductor manufacturing system is provided. Plural first transistors are formed and a first VtMM value and a first scale value are obtained. Plural second transistors are formed and a second VtMM value and a second scale value are obtained. Plural third transistors are formed and a third VtMM value and a third scale value are obtained. A first channel length of the first transistor is smaller than a second channel length of the second transistor and is equal to a third channel length of the third transistor. A VtMM v.s. scale figure is established. A line is formed by linking the first dot and the third dot and a vertical Gap between the line and the second dot is measured. The capability of the semiconductor system is determined based on the vertical Gap. The invention further provides a chip.
1. Field of the Invention
The present invention relates to a semiconductor chip and a method of estimating the capability of a semiconductor manufacturing system, and more particular, the present invention relates a semiconductor chip with memory arrays and a method of estimating the capability of a semiconductor manufacturing system for forming memory cells.
2. Description of the Prior Art
For decades, chip manufacturers have made metal-oxide-semiconductor (MOS) transistors faster by making them smaller. As the semiconductor processes advance to very deep sub-micron era such as 65-nm node or beyond, how to form smaller device has become a critical issue.
For improving the semiconductor manufacturing system, many parameters should be considered, one of which is “length with roughness (LWR)”. Please see
It is therefore one objective of the invention to use the LWR to determine the capability of the semiconductor manufacturing system.
According to one embodiment, a method of estimating the capability of a semiconductor manufacturing system is provided. Plural first transistors are formed and a first VtMM value and a first scale value are obtained. Plural second transistors are formed and a second VtMM value and a second scale value are obtained. Plural third transistors are formed and a third VtMM value and a third scale value are obtained. A first channel length of the first transistor is smaller than a second channel length of the second transistor and is equal to a third channel length of the third transistor. A VtMM v.s. scale figure is established. A line is formed by linking the first dot and the third dot and a vertical Gap between the line and the second dot is measured. The capability of the semiconductor system is determined based on the vertical Gap.
According to another embodiment, the invention further provides a semiconductor chip. The semiconductor chip comprises a plurality of first transistors in a first memory region and a plurality of second transistors in a second memory region, wherein a first channel length of the first transistor is smaller than a second channel length of the second transistor.
By measuring the VtMM and the scale value of the transistors, a “VtMM v.s. scale” figure is established and the Gap is obtained. The Gap represents the LWR and can be used to determine the capability of the semiconductor manufacturing system.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
To provide a better understanding of the presented invention, preferred embodiments will be made in detail. The preferred embodiments of the present invention are illustrated in the accompanying drawings with numbered elements.
Please refer to
Step 302: forming a plurality of first transistors in a first memory region by a semiconductor manufacturing system, and obtaining a first threshold voltage mismatch (VtMM) value and a first scale value of the first transistors;
Step 304: forming a plurality of second transistors in a second memory region by the semiconductor manufacturing system, and obtaining a second VtMM value and a second scale value of the second transistors;
Step 306: forming a plurality of third transistors in a third memory region by the semiconductor manufacturing system, and obtaining a third VtMM value and a third scale value of the third transistors;
Step 308: establishing a VtMM v.s. scale figure;
Step 310: forming a line by linking the first dot and the third dot, and measuring a vertical gap between the line and the second dot;
Step 312: estimating the capability of the semiconductor system based on the vertical Gap.
For the detail description of the above-mentioned method, please refer to
The scale value=1/(the channel length×the channel width)1/2 (equation 1)
The scale value indicates the scaling down level of a device, and the bigger the scale value is, the smaller the device is. In addition, one or more than one electrical process can be performed to measure a first threshold voltage mismatch (VtMM) of the first transistors 402. The VtMM value is a variation value (a) of the threshold voltages of the first transistors 402. The bigger the VtMM value is, the variation of each Vt is larger, meaning that the semiconductor manufacturing system is poor because all the first transistors should ideally have the same threshold value.
Next, a plurality of second transistors are formed by the same semiconductor manufacturing system for forming the first transistors (step 304). In one embodiment, the second transistors are disposed in a second memory region. Preferably, the second transistors and the second memory region have similar components and arrangements with those of the first transistors and the first memory region. As shown in
Nest, a plurality of third transistors are formed by the same semiconductor manufacturing system for forming the first transistors (Step 306). The third transistors are disposed in a third memory region. Preferably, the third transistors and the third memory region have the similar components and arrangements with those of the first transistors and the first memory region. As shown in
It is noted further noted that that the sequence of forming the first transistors 402, the second transistors 502 and the third transistors 602 can be adjusted arbitrarily or they can be formed simultaneously if they are in the same wafer.
After obtaining the first scale value, the first VtMM value, the second scale value, the second VtMM value, the third scale value and the third VMM value, a “VtMM v.s. scale” figure can be established (step 308). Please see
Next, as shown in
Accordingly, the Gap can be used to estimate the capability of the semiconductor manufacturing system for forming the first transistors 402, the second transistors 502 and the third transistors 602 (step 312). If the Gap is within an acceptable value, the semiconductor manufacturing system is capable of performing processes with least errors. However, if the Gap exceeds an acceptable value, it means that the LWR effect is too large and the semiconductor manufacturing system should be reconsidered because it cannot form precise pattern. By providing the above-mentioned process, the LWR can be easily obtained by measuring the Gap so as to estimate the capability of the semiconductor manufacturing system.
It is noted that, in the present invention, the first transistors 402, the second transistors 502 and the third transistors 602 are not necessary in the same wafer or die. In one embodiment, they are in the same wafer or die, and in another embodiment, two of whom are in the same wafer or die. In one embodiment, by performing the method shown above, the second transistors 502 are used as a “testkey” structure in a small region, together with the mass-produced first transistors 402 and/or the mass-produced third transistors 602, so as to perform the method in the present invention. Accordingly, the present invention further provides a chip structure with the above features. Please see
In summary, the present invention provides a semiconductor chip and a method of monitoring the LWR value in a semiconductor manufacturing system. By measuring the VtMM and the scale value of the transistors, a “VtMM v.s. scale” figure is established and the Gap is obtained. The Gap represents the LWR and can be used to determine the capability of the semiconductor manufacturing system.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A method of estimating the capability of a semiconductor manufacturing system, comprising:
- forming a plurality of first transistors in a first memory region by using a semiconductor manufacturing system, and obtaining a first VtMM value and a first scale value based on the first transistors;
- forming a plurality of second transistors in a second memory region by using the semiconductor manufacturing system, and obtaining a second VtMM value and a second scale value based on the second transistors;
- forming a plurality of third transistors in a third memory region by using the semiconductor manufacturing system, and obtaining a third VtMM value and a third scale value based on the third transistors, wherein a first channel length of the first transistor is smaller than a second channel length of the second transistor and is equal to a third channel length of the third transistor;
- establishing a VtMM v.s. scale figure and plotting a first dot corresponding to the first VtMM value and the first scale value, a second dot corresponding to the second VtMM and the second scale value, and a third dot corresponding to the third VtMM value and the third scale value on said figure;
- forming a line by linking the first dot and the third dot;
- measuring a vertical Gap between the line and the second dot; and
- estimating the capability of the semiconductor system based on the vertical Gap.
2. The method of estimating the capability of a semiconductor manufacturing system according to claim 1, wherein the first memory region, the second memory region and the third memory region are in a memory region.
3. The method of estimating the capability of a semiconductor manufacturing system according to claim 2, wherein the memory region is a Static Random-Access Memory (SRAM) memory region.
4. The method of estimating the capability of a semiconductor manufacturing system according to claim 2, wherein the memory region is a 6-transistors (6T) SRAM memory cell region.
5. The method of estimating the capability of a semiconductor manufacturing system according to claim 1, wherein each first transistor further comprises a first channel width, each second transistor further comprises a second channel width, and each third transistor further comprises a third channel width.
6. The method of estimating the capability of a semiconductor manufacturing system according to claim 5, wherein the first channel width is equal to the second channel width.
7. The method of estimating the capability of a semiconductor manufacturing system according to claim 5, wherein the first channel width is smaller than the third channel width.
8. The method of estimating the capability of a semiconductor manufacturing system according to claim 5, wherein the first scale value, the second scale value and the third scale value are obtained by the following equation:
- the scale value=1/(the channel length×the channel width)1/2
9. The method of estimating the capability of a semiconductor manufacturing system according to claim 1, wherein the first VtMM value, the second VtMM value and the third VtMM value are variation values of the threshold voltage of the first transistors, the second transistors and the third transistors respectively.
10. The method of estimating the capability of a semiconductor manufacturing system according to claim 1, wherein the larger the Gap is, the less capability of the semiconductor manufacturing system is.
11. A semiconductor chip, comprising a plurality of first transistors in a first memory region and a plurality of second transistors in a second memory region, wherein each first transistor has a first gate structure and each second transistor has a second gate structure, and a first gap is disposed between each of two adjacent first gate structures and a second gap is disposed between each of the two adjacent second gate structures, a first channel length of the first transistor is smaller than a second channel length of the second transistor, and (the first channel length+the first gap)=(the second channel length+the second gap).
12. The semiconductor chip according to claim 11, wherein the first memory cell region and the second memory cell region are in a memory region.
13. The semiconductor chip according to claim 12, wherein the memory region is a Static Random-Access Memory (SRAM) memory region.
14. The semiconductor chip according to claim 12, wherein the memory region is a 6-transistors (6T) SRAM memory cell region.
15. (canceled)
16. The semiconductor chip according to claim 11, further comprising a plurality of third transistors in a third memory region.
17. The semiconductor chip according to claim 11, wherein a third channel length of the third transistor is equal to the first channel length.
18. The semiconductor chip according to claim 11, wherein each first transistor further comprises a first channel width, each second transistor further comprises a second channel width, and each third transistor further comprises a third channel width.
19. The semiconductor chip according to claim 18, wherein the first channel width is equal to the second channel width.
20. The semiconductor chip according to claim 18, wherein the first channel width is smaller than the third channel width.
Type: Application
Filed: Oct 7, 2014
Publication Date: Apr 7, 2016
Inventors: Wei-Chi Lee (Tainan City), Yu-Lin Wang (Taipei City), Chun-Chieh Chang (Tainan City), Tzu-Feng Chang (Pingtung County), Po-Peng Lin (Tainan City)
Application Number: 14/509,032